I don't see perl being used for the systems control software in a nuclear power station.
I realize you are half-joking here, but still, I have seen this exact same sentence quite a few times now so I will answer it here.
I don't think the language used for the systems control software in a nuclear power station is really relevant. I would bet that along the ages such systems have been written in assembly language, Fortran, probably COBOL, C, C++, possibly ADA... none of which strike me as being really "safer" than Perl, whatever "safer" might mean. All that matters is that the development methodology is sound, that the software is tested extensively and that the developers know what they are doing. Perl, maybe with a touch of C for those really time-critical bits, would do just fine there.
And BTW, I have never seen the code for such a control system, but I have been in contact with people that manage it, and believe me, it looks like a huge mess, just like any other project I have seen that involves dozens of subcontractors and hundreds of developers.
